The use of infinite switch energy regulators are well known in the art of energy and load control. For example, infinite switch energy regulators are employed in electric ranges, to control the energy supplied to a load, such as a burner. In a typical infinite switch energy regulator, depending on the setting of the switch, a duty cycle is selected to be provided as an output from the energy regulator to the load. An infinite switching type energy regulator works on the principle that if the contacts are opened and closed at different on-to-off time ratios, or different duty cycles, sometimes referred to as % (percent) on-times, the energy transmitted to a physical mass, through an electrical load, can be regulated as those ratios are varied. However, in order to regulate the temperature of the heating element to which the electrical power is supplied, the on/off switching of electrical energy requires that the cooktop heating element (load) and physical mass in contact with the heating element, such as a pot or pan with water or food, have a significant lumped thermal capacitance.
An infinite switching type energy regulator typically has a bimetal coupled to a cycling contact and an internal heater that causes the bimetal to deform when energy is applied to the internal heater and the resistive load. As the load and the internal heater are heated, the bimetal deforms and the switch is opened. The cycling contact closes, due to spring forces, after the bimetal has cooled sufficiently to allow it to deform back to its original ambient temperature shape. An infinite switch energy regulator is typically employed in a 240 volt ac application and the internal heater and collaboration are configured for use in such an application.
One of the problems with the presently available energy regulator, which uses only 240 volt ac, is that the load exhibits much greater changes in instantaneous temperature as the infinite switch energy regulator cycles on and off. To a household user, this means that certain foods, such as chocolates and sauces, tend to burn in a 240 volt ac system due to the instantaneous changes in temperature.
In certain high-end ranges, a toggle switch is provided on the front panel of the electric range to select between 120 volts ac and 240 volts ac. The separate toggle switch is electrically connected to the infinite switch energy regulator, which is separately controlled by a user. By switching to a 120 volt ac mode using the toggle switch, the infinite switch energy regulator in these high-end ranges can provide a very gentle simmer. The toggle switch feeds the 120 volt ac to the infinite switch energy regulator. The infinite switch used in such high-end ranges is normally used in 240 volt ac applications. Hence, when the voltage is dropped to half of its design value, (i.e., 120 volt ac), both the internal and external heaters and resistive load are now supplied with one-fourth (¼) of the original power. As the internal heater causes the bimetal to deform, which is the prime mover for the cycling of energy regulating contacts, then at 120 volt ac it takes more time to deform the bimetal to a given geometry than at 240 volt ac. The amount of deformation is critical to the operation of an infinite switch because the internal components reposition themselves to the point where the contacts, and hence the circuit open, within the infinite control, thereby cycling the current.
As stated earlier, an infinite control's cycling contact closes, typically due to spring forces, after the bimetal has cooled sufficiently to allow it to deform back to its original ambient temperature shape. The time it takes for the bimetal to cool does not change significantly whether 120 volt ac or 240 volt ac is supplied to the infinite switch energy regulator. When power is no longer applied, and since the bimetal mechanism has reached the same physical state at 120 volt ac as at 240 volt ac (although taking more time to do so), the rate of energy dissipation is dictated by the thermal properties of the materials and surroundings. These parameters are not affected by a voltage which is no longer being applied, so that voltage is the only variable that changes.
Since the high-end ranges apply power for a longer period than normal in 120 volt ac mode than in 240 volt ac mode, with a cooling time remaining roughly constant, the duty cycle increases by a factor of four when the voltage is decreased to one-half. The effect to a substantial mass, such as a gallon of water, is negligible, because over a large period of time (e.g., an hour), the pot of water reaches the same steady state temperature whether the system utilized 120 volt ac or 240 volt ac in the manner described above. The reason for this is that although only one-fourth the power is being applied, it is being applied for four times the effective duty cycle, so that in effect, the total amount of energy being transferred to the physical mass remains constant. However, if a mass of non-substantial quantity is placed in physical contact with a thermal/electrical load, then a significant change in performance occurs. Although the steady state or average temperature theoretically remains constant, the instantaneous temperature changes exhibit a very noticeable difference when switching between 120 volt ac and 240 volt ac modes. The physical mass undergoes very slight temperature changes when in the 120 volt ac mode. Hence, by toggling to a 120 volt ac mode, a very gentle simmer of delicate foods, such as chocolates and sauces, may be achieved.